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#include "../../include/std/file.h"
#include "../../include/std/mem.h"
#include "../../include/std/log.h"
#include <stdio.h>
#include <errno.h>
#include <assert.h>
#include <string.h>

#include <dirent.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <unistd.h>

#define SCANDIR_PATH_LENGTH 4096

static int scan_dir_recursive_internal(char *dir_path, int path_length, scan_dir_callback_func callback_func, void *userdata) {
    DIR *dir;
    struct dirent *entry;
    struct stat file_stats;
    int filename_length;
    int path_length_start;

    path_length_start = path_length;
    if((dir = opendir(dir_path)) == NULL) {
        amal_log_perror("scan_dir_recursive");
        return errno;
    }

    while((entry = readdir(dir)) != NULL) {
        /*
        Skip hidden files. Name will always at least include null terminator
        so it's ok to not check filename length. And file names are never empty, right???
        */
        if(entry->d_name[0] == '.')
            continue;

        /* Reset path concat, because it's overwritten by recursive call to scan dir */
        path_length = path_length_start;
        filename_length = strlen(entry->d_name);
        /* current path '/' filename '\0' */
        if(path_length + 1 + filename_length + 1 > SCANDIR_PATH_LENGTH) {
            amal_log_error("Filepath too long. Trying to append %s to %s", entry->d_name, dir_path);
            return -1;
        }

        /* Replace '\0' with '/' */
        dir_path[path_length] = '/';
        ++path_length;
        am_memcpy(&dir_path[path_length], entry->d_name, filename_length);
        path_length += filename_length;
        dir_path[path_length] = '\0';
        
        if(stat(dir_path, &file_stats) == -1) {
            amal_log_perror("scan_dir_recursive_internal");
            goto cleanup;
        }

        if(S_ISDIR(file_stats.st_mode)) {
            cleanup_if_error(scan_dir_recursive_internal(dir_path, path_length, callback_func, userdata));
        } else if(S_ISREG(file_stats.st_mode)) {
            if(!callback_func(dir_path, path_length, userdata))
                goto cleanup_noerr;
        } else if(S_ISLNK(file_stats.st_mode)) {
            amal_log_warning("Symlink ignored: %s", entry->d_name);
        } else {
            /* Ignore block devices and all other types of files */
        }
    }

    cleanup_noerr:
    closedir(dir);
    return 0;

    cleanup:
    closedir(dir);
    return -1;
}

int scan_dir_recursive(const char *dir_path, scan_dir_callback_func callback_func, void *userdata) {
    char scandir_path[SCANDIR_PATH_LENGTH];
    int dir_path_length = strlen(dir_path) + 1; /* include null terminator */
    am_memcpy(scandir_path, dir_path, dir_path_length);
    return scan_dir_recursive_internal(scandir_path, dir_path_length - 1, callback_func, userdata);
}

static int mapped_file_mode_to_system_file_mode(MappedFileMode file_mode) {
    switch(file_mode) {
        case MAPPED_FILE_READ:          return PROT_READ;
        case MAPPED_FILE_WRITE:         return PROT_WRITE;
        case MAPPED_FILE_READ_WRITE:    return PROT_READ | PROT_WRITE;
        default:
            assert(bool_false);
            return PROT_READ;
    }
}

int mapped_file_init(MappedFile *self, const char *filepath, MappedFileMode file_mode) {
    struct stat file_stats;
    int fd;
    const char *memblock;
    int map_file_system_mode;

    self->file_data = NULL;
    self->file_size = 0;
    self->fd = -1;

    fd = open(filepath, O_RDONLY);
    if(fd == -1) return errno;
    if(fstat(fd, &file_stats) == -1) {
        amal_log_perror("map_file_read");
        goto cleanup;
    }

    map_file_system_mode = mapped_file_mode_to_system_file_mode(file_mode);
    memblock = mmap(NULL, file_stats.st_size, map_file_system_mode, MAP_PRIVATE, fd, 0);
    if(memblock == MAP_FAILED) {
        amal_log_perror("map_file_read");
        goto cleanup;
    }

    self->file_data = memblock;
    self->file_size = file_stats.st_size;
    self->fd = fd;
    return 0;

    cleanup:
    close(fd);
    return -1;
}

int mapped_file_deinit(MappedFile *self) {
    int result_munmap;
    int result_close;

    if(!self->file_data)
        return 0;
    
    result_munmap = munmap((void*)self->file_data, self->file_size);
    if(result_munmap == -1)
        amal_log_perror("mapped_file_deinit");
    result_close = close(self->fd);
    if(result_close == -1)
        amal_log_perror("mapped_file_deinit");
    self->file_data = NULL;
    self->file_size = 0;
    self->fd = 0;
    if(result_munmap == -1 || result_close == -1)
        return -1;
    else
        return 0;
}